Display screen or portion thereof with an icon



FIG. 1 is a front view of a first embodiment of a display screen or portion thereof with an icon showing my new design;

FIG. 2 is a front view of a second embodiment of a display screen or portion thereof with an icon showing my new design;

FIG. 3 is a front view of a third embodiment of a display screen or portion thereof with an icon showing my new design; and,

FIG. 4 is a front view of a fourth embodiment of a display screen or portion thereof with an icon showing my new design.

The broken line showing of a display screen or portion thereof forms no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with an icon, as shown and described. 